THE familiar map of Wales could look very different by the end of the century due to a huge change in the shape of our coastline, a report warns today.
The National Trust in Wales is the latest body to warn that rising sea levels caused by unchecked global warming could lead to widespread disaster.
The report, Shifting Shores, shows that more than 70% of the coastline that the National Trust manages in Wales, much of it internationally renowned, is under threat from coastal erosion and flooding.
The land covers more than 143 miles bordering the sea - a sixth of the Welsh coastline.
The report is published on the day that the National Assembly discusses a Conservative call for the Welsh Assembly Government to make radical action to combat climate change its top priority.
The National Trust echoes the call and says policy makers must act now to draw up long-term strategies to help communities and businesses adapt to an expected rise of up to one metre in sea levels by the end of the century.
"Over the next few decades, flooding and erosion caused by sea level rise and more frequent storms appear inevitable," said Iwan Huws, National Trust director for Wales.
The UK Climate Change Impacts Programme warned last month that sea levels around the UK will rise by up to 86cm by the year 2080. It said that frequent tidal surges and severe storms will make erosion and flooding even worse.
Sir Nicholas Stern, head of the UK Government's economic service and chief government adviser on the economics of climate change, warned of devastating human and economic consequences.
In Wales it is not just National Trust land which will be affected - the capital itself, along with most of the major centres of population, are at risk.
Environment Agency Wales says there are likely to be significant impacts across the region.
A spokesman said, "The Severn Estuary is at high risk of flooding and the Lleyn Peninsula, inner Severn and Dee Estuary are vulnerable to coastal erosion and damage to coastal defences.
"The vulnerability of the Welsh coast poses problems for a large proportion of the population living in coastal communities, affecting the waste infrastructure - landfills, incinerators and waste transfer facilities - and transport infrastructure, rail and road."
The agency is developing maps of the likely effects of sea level rises as part of its overall flood mapping strategy.
And it is building coastal defences that allow for a 5mm increase in sea levels per year over the life of each new scheme - with allowances for higher defences to be incorporated in future years. The National Trust report is a further indication of the growing awareness of the devastation that would accompany the higher sea levels and greater tidal and storm surges that experts now agree will result from climate change.
Eluned Morgan MEP warned the National Assembly last year that rising sea levels could drown the landmark £67m Senedd building itself.
Wales Environment Minister Carwyn Jones called the National Trust report "an important piece of research that will contribute significantly to the debate on potential impacts of climate change in Wales and how we can adapt to these impacts".
The National Trust says 66 of the coastal sites it owns or manages in Wales - covering 3,885 acres - are at risk of flooding and two sites are vulnerable to combined tidal and river flooding.
They include the Stackpole Estate in Pembrokeshire with the popular Bosherston Lily Ponds; Cemlyn lagoon on Anglesey, an important wildlife site; dune systems on Gower and historic sea forts such as Dinas Dinlle near Llandwrog. Julian Rosser, director of Friends of the Earth Cymru, said the latest report showed how widespread the devastation could be, without taking into account the dramatic impacts on people and property in a country where so much of the population lives on or near the coast.
"We really have to have urgent action by politicians," he said.
"We need them to have the courage to stick their necks out and take radical action, but we feel there's a lack of leadership in the National Assembly."
A spokesman for the Pembrokeshire Coast National Park Authority said it recognised the potential impacts of climate change and the vulnerability of certain areas of the park.
He said, "We are responding to the Assembly Government's consultation paper on planning and climate change and are reviewing our development and management planning policies in the light of the challenges posed by climate change."